Field of the Invention
The invention relates in general to an electronic device, and more particularly to a buffer circuit, a display module and a display driving method.
Description of the Related Art
Along with the popularity of display products, liquid crystal display (LCD) products are widely used in people's everyday life. For an LCD to display frames properly, a digital to analog converter (DAC) is used to convert digital signals of image data into analog signals for driving liquid crystal molecules. During the process of converting the digital signals into the analog signals, the DAC employs several levels of gamma reference voltages.
Referring to FIG. 1, a schematic diagram of a positive resistance string, a negative resistance string, a positive polarity buffer and a negative polarity buffer is shown. Since liquid crystal molecules involve polarity conversion, a driver chip normally has a positive resistance string 32 and a negative resistance string 33 respectively representing the voltages at the positive and negative polarities of the driver chip. The positive resistance string 32 and the negative resistance string 33 are also referred as gamma resistors. A positive buffer amplifier 35 provides voltage to the positive resistance string 32. A negative buffer amplifier 36 provides voltage to the negative resistance string 33.
Each position of the positive buffer amplifier 35 on the positive resistance string 32 defines a dividing point, and each position of the negative buffer amplifier 36 on the negative resistance string 33 defines a dividing point. Then, each dividing point enters the DAC, which determines the output voltage and polarity of the driver chip according to the input signals. Since the resistance is inversely proportional to the current consumption, the driver chip will consume hundreds of micro-amperes to a few milliamps on the positive resistance string 32 and the negative resistance string 33, and such amount of current consumption occupies a large proportion of overall current consumption of the driver chip.